Popcorn is a highly popular snack food item. In the past, the at-home preparation of popcorn by the consumer involved adding kernel popcorn plus a cooking oil to a covered pot and heating until the popcorn kernels popped to make popcorn. As used herein, "kernel popcorn" refers to unpopped popcorn. The noun "popcorn" or synonymously "popped popcorn" refers herein to popped kernel popcorn. The adjective "popcorn" can refer to either. Once prepared, common, relatively coarse, table salt is a frequently added flavoring or condiment. The resultant salted popped popcorn is a familiar snack food.
More recently, microwave popcorn products have become extremely popular. At present, in the U.S., over 70 different brands of microwave popcorn products are available. In general, the more popular microwave popcorn products comprise an expandable paper bag containing a charge of kernel popcorn, fat and salt. The microwave popcorn article is adapted to be heated in a microwave oven for three to five minutes to produce the popped popcorn. More recently, improved microwave popcorn articles have been fabricated employing a metallized susceptor which facilitates the heating of the kernel popcorn-fat charge and which, in turn, leads desirably to increases in popcorn volume and decreases in unpopped kernels. Microwave popcorn articles of this type are described in detail in, for example, U.S. Pat. No. 4,450,180 (issued May 22, 1984 to J. D. Watkins and incorporated herein by reference).
Microwave popcorn articles, of course, comprise a microwave popping bag and a charge of kernel popcorn, fat, and, usually, salt. Certain early patents taught the addition of kernel popcorn, fat that is solid at room temperature and salt in the form of a prefabricated toroid or doughnut shaped piece. The piece was fabricated by mixing the kernel popcorn, salt and melted fat to form a blend and the blend was allowed to cool and harden into the toroid shape desired. These circular pieces were then dropped into the desired chamber of the popcorn bag prior to final sealing. (See for example U.S. Pat. No. 4,450,180, issued May 22, 1984).
Contemporary methods of filling microwave popcorn bags, however, employ a different filling process and technique. (See, for example, U.S. Pat. No. 4,604,854 entitled "Machine For Forming, Filling and Sealing Bags," issued Aug. 12, 1986 to D. W. Andreas). The microwave bags having an unsealed open end are advanced to a first kernel popcorn filling station. While being maintained in an open position, the kernel popcorn is charged to the desired channel. Thereafter, the bags are advanced to a second filling station at which the fat/salt slurry is added to the bag. Prior to filling, the fat is heated to well above its melting point to form a liquid oil. Typically, the slurry is added in the form of a vertically dispensed pencil jet (i.e., a confined stream) of the slurry. Single station filling methods are also known that involve applying the fat/salt slurry as a spray onto the kernel popcorn as the kernel popcorn falls into the bag. (See, for example WO 95/01105 entitled "Reduced Fat Microwave Popcorn and Method of Preparation" published Jan. 12, 1995, or, equivalently, U.S. Pat. No. 5,690,979 issued Nov. 25, 1997 which is incorporated herein by reference). Such single station filling techniques are especially useful for the preparation of low fat microwave popcorn products.
The bags now containing both kernel popcorn and slurry are then advanced to a sealing station where the bags are provided with a top seal to complete the closure of the bag. The sealed popcorn bags are advanced to subsequent finish packaging operations which complete the folding of the bags, providing the bags with an overwrap, and inserting appropriate numbers of the bags into cartons, etc.
Current varieties of microwave popcorn products include full fat products (e.g., 20-35% fat), reduced fat (10-20% fat) and low fat products (10%).
Regardless of fat content, conventional microwave popcorn products generally employ a partially hydrogenated vegetable oil (usually soybean oil) which is solid at room temperature. This increases oil stability and provides a solid oil or fat, which is less prone to wicking out of the bag during extended storage. A typical melting point for such an oil would be about 106.degree. F. (41.1.degree. C.)
One processing problem is that during the winter months (when the corn is desirably fresh from harvest), bulk corn may reach temperatures significantly below room temperature (e.g., 30 to 50.degree. F.), due to outside storage and bulk rail or truck transportation. In the manufacture of reduced fat or low fat microwave popcorn products, when the relatively small amount of hot oil slurry is applied to the cold corn (typically about 5 grams of oil slurry to 85 grams of corn), the cold corn causes the slurry to set very rapidly while the bag articles are still in the filling machine. This undesirably results in a bulky, non-pliable bag, which is more prone to jamming during the rest of the filling. The manufacture of higher fat containing popcorn products such as full fat microwave popcorn articles is less prone to these manufacturing problems since there is enough mass of warm, 125.degree. F. oil, that the cold corn can't crystallize enough of the oil quickly enough to cause setting up of the oil.
Of course, one way of overcoming these seasonal manufacturing problems would be to warm the corn prior to filling in the manufacturing of the microwave popcorn articles. However, since the finished articles are returned to storage under uncontrolled winter temperatures, such heating is neither economical nor energy efficient. Another solution is to defer manufacture after corn harvest until the following warm season and to complete the manufacture of an entire year's consumption of microwave popcorn within the warm season. Particularly in the upper midwest of the United States having long winter seasons, this solution is neither practical nor economical. Still another technique is to heat the hydrogenated fat to much higher oil temperatures. However, providing an oil supply maintained at such higher temperatures can adversely degrade desirable butter flavors or butter derived constituents added to the oil.
Surprisingly, the seasonal manufacturing problems can be overcome in the manufacture of lowfat and reduced fat microwave popcorn articles.
A surprising, simple, novel solution to this problem to use a liquid oil in place of the typical solid fat.
Such a liquid oil may have a melting point of about 60.degree. F. or less. Since the oil is a liquid, even at room temperature, coming into contact with the cold corn during filling just decreases the oil temperature, without causing a phase change in the oil. Without any setting of the oil, the end result is a much more pliable bag, which does not jam in the filling equipment.
Another advantage of employing liquid oil is that such oil is lower in undesirable saturated fat and trans fatty acids.
In view of the prior art and the problems described above, there is a continuing need for new and useful microwave popcorn products that are reduced or low in fat that nonetheless can be easily manufactured even during cold months. Accordingly, it is an object of the present invention to provide microwave popcorn products reduced fat levels that are formulated to facilitate manufacture even when using cold corn.
In particular, it is an object of the present invention to provide methods for preparing reduced and low fat microwave popcorn products having at least a major portion of the fat component supplied by an oil that is liquid at room temperature and below.
In view of these processing difficulties, a further important object of the present invention is to provide for commercially practical methods for reduced fat and low fat microwave popcorn products.
Still another object of the present invention is to provide methods for prepared calcium fortified microwave popcorn products wherein the popcorn is processed at cold temperatures.
Still another object of the present invention is to provide microwave popcorn fat components that are naturally low in trans fatty acids.
It has been surprisingly discovered that the above objectives can be realized and superior microwave popcorn products provided by formulating food charge compositions disposed with microwave popcorn bags, comprising popcorn, optionally salt and low levels of liquid oils having a melting point of about 60.degree. F. or lower.